LinearDragger: a Linear Selector for One-finger Target Acquisition

Touch input is increasingly popular nowadays, especially for mobile devices such as smartphones and tablet computers. However, the human finger has considerably large fingertip size and finger input is imprecise. As such, acquiring small targets on a touch screen is still a challenging task. In this paper, we present the LinearDragger, a new and integrated one-finger target acquisition technique for small and clustered targets. The proposed method has three advantages. First, it allows users to select targets in dense clustered groups easily with a single touch-drag-release operation. Second, it maps the 2D selection problem into a more precise 1D selection problem, which is independent of the target distribution. Third, it avoids finger occlusion and does not create visual distraction. As a result, it is particularly suitable for applications with dense targets and rich visual elements. Results of our controlled experiments show that when selecting small targets, LinearDragger takes about 70% and 30% less selection time than target acquisition without using any techniques and with the state-of-the-art target acquisition technique that involves a single touch operation, respectively, while maintaining a reasonable error rate.